1. Field of the Invention
This invention relates to fasteners, and more particularly to a maintenance free fastener and bearing combination adapted to pivotably couple a plurality of members to one another.
2. Background Information
Many applications call for convenient means for rotatably or pivotably fastening multiple members to one another in a maintenance free manner. Examples of such applications include multiple bar linkages commonly utilized in the automotive industry for trunk deck lid and hood hinges, and as window stays adapted to raise and lower windows. Additional applications may include collapsible baby carriages or strollers, beach chairs, recliners, toys, automobile seats, or substantially any other application involving pivotable movement. For example, it is common to couple two arms of a window stay or a hood hinge linkage using a rivet, pin or similar fastener that extends through two apertures formed one in each of the adjacent ends of the arms to be joined. A bushing formed of a self-lubricating material such as nylon or suitable plastic material is interposed between the rivet and the arms to prevent metal to metal contact in the joint between moving parts of the arms and rivet. In some instances, a washer may be installed concentrically about the bushing between the two arms to facilitate the rotational movement of the arms relative to one another and help prevent binding.
Moreover, in a variation of the above approach, it is often desirable to utilize a two-part bushing to facilitate manufacturability and to provide enhanced pivotal movement. In this regard, the bushing is essentially provided in two discrete half portions. A first half portion is permanently installed and captured, such as by swaging or flanging operations, in the aperture of the first arm, while a second half portion is similarly installed in the aperture of the second arm. A fastener such as a rivet is then installed in a conventional manner into both halves of the bushing to join the arms to one another.
While the foregoing approach may operate satisfactorily, it is not without drawbacks. In particular, the configuration utilizes a relatively high number of discrete components, each of which must be separately inventoried and installed. This tends to add undesirable complexity and expense to the overall assembly.
Furthermore, it is important that such joints be accurately formed so that the joint is relatively tight and the fastener or rivet, which holds the joint together, is properly oriented. If the rivet is off-center within the apertures and/or canted to an oblique angle relative to the axes of the apertures during manufacture or operation, due to, for example, insufficiently loose tolerances, the joint will be inaccurately formed and the arms will not be maintained in parallel orientation to one another. Any misalignment at the joint is magnified at the distal ends of the arms and thus it is important that such joints are so constructed as to minimize such difficulties. In addition, joints that are excessively loose when installed in, for example, automobiles, may tend to undesirably rattle during vehicle operation. For these reasons, and to help prevent the joints from loosening prematurely upon repeated use, it is desirable to manufacture the joint components to relatively tight tolerances.
In this regard, generally speaking, tolerance stacking and other factors afford assemblies fabricated with a relatively large number of discrete components with greater opportunities for misalignment and mechanical loosening than similar assemblies fabricated from fewer discrete components. It thus may be desirable to hold components of the former assemblies to tighter tolerances than those of the latter. Those skilled in the art will recognize that tighter tolerances tend to relatively increase the expense of component manufacture.
A need thus exists for an improved maintenance free fastener and bearing combination that utilizes fewer components and otherwise overcomes the problems of the prior art.